Field of the Invention
The disclosure relates to a liquid discharge head that includes a printed circuit board.
Description of the Related Art
Wire bonding is known as a method of connecting a pad of a printed circuit board and a pad of an electrical wiring board to each other. In wire bonding, an electrical wiring board is bonded to a portion of a printed circuit board located in the vicinity of a pad on the printed circuit board, after which the pad of the printed circuit board and a pad of the electrical wiring board are connected to each other with a bonding wire. In order to perform wire bonding, each of the pads needs to be positioned as horizontally as possible. Consequently, it is desirable that the electrical wiring board be bonded to a flat portion of the printed circuit board.
In the manufacture of a printed circuit board, the printed circuit board is entirely covered with a resist from above wiring lines of the printed circuit board, and an inclination of a surface layer of the resist derived from the irregularities of the wiring lines may sometimes occur due to the thicknesses of the wiring lines, the widths of the wiring lines, the pitch of the wiring lines, and the thickness of the resist covering the wiring lines. In a method disclosed in Japanese Patent Laid-Open No. 2010-186769, irregularities and an inclination of a surface layer of a resist due to wiring lines is suppressed by performing several times a process of forming an insulating layer (resist) after an electrically conductive layer has been formed.
However, in the case of providing a plurality of resist layers as described in Japanese Patent Laid-Open No. 2010-186769, the number of resist-layer application steps and the number of resist-layer removing steps increase, which in turn results in a decrease in manufacturing efficiency.